UPDATE, 5:38 p.m.: Bethesda's Second District police station has re-opened following a Thursday afternoon evacuation.
The station was shut down for nearly an hour and a half -- from 3:25 p.m. to 4:50 p.m. -- after a resident attempted to turn in an old grenade, according to Montgomery County Police Spokeswoman Blanca Kling.
Montgomery Avenue was also re-opened after being closed.
WUSA9 is reporting a woman who was cleaning her home found the grenade and attempted to turn it in. A fire marshal removed the grenade and rendered it safe, but it wasn't clear whether it was live, according to WUSA9.
The woman who found the grenade had been preparing to sell her home, WUSA9 reported.
Original Post, 4:12 p.m.: Bethesda's is being evacuated and Montgomery Avenue is shut down after a resident tried to turn in an old grenade to authorities, Montgomery County Police report.
Montgomery County Police tweeted Thursday afternoon that the station was shut down for an investigation. Police Spokeswoman Angela Cruz told Patch a resident came to the station to turn over a grenade. The person didn't make threats and the station was being evacuated as a precaution, Cruz said.
The fire marshal was being called to the scene to investigate.
Commuters are being asked to avoid the police station, located at the intersection of Wisconsin and Montgomery avenues.
This post will be updated as more information becomes available.